Lactic acids have been prepared from starchy agricultural products such as rice, potatoes, corns, and rice bran. In prior illustrative methods, these agricultural products have been subjected to the following steps to produce lactic acids: gelatinization, saccharification, inoculation, fermentation, precipitation, crystallization, acidolysis, concentration, etc.
Without wishing to be bound by the theory, Applicant believes that fermentation was an important step in the formation process. During the fermentation step, germ has been added to the agricultural products subjected to gelatinization and saccharification, in order to prepare polylactic acids. The process to prepare lactic acids, however, is a reversible process, which tends to retard, or stop, the fermentation process. In order to improve production, calcium carbonates (CaCO3) may have been added to the fermentation solution to react with the lactic acids and produce calcium lactate. In this manner, the amount of lactic acid produced in the fermentation solution was decreased and the fermentation process may proceed. After completion of the fermentation process, sulfuric acids may have been added to the calcium lactate in order to release the lactic acids by acidolysis.
The lactic acids may have been polymerized to form polylactic acid (“PLA”). PLA may be degraded by natural microorganisms, which may release carbon dioxide and water. The degradation may be generally “environmentally friendly,” and PLA may have had fairly good biocompatibility and biodegradability.